This invention relates to an apparatus and method for treating cardiac or similar conditions in a patient. More specifically, this invention relates to mapping of, and application of laser energy, to the tissues of a patient.
The use of laser beams for treatment of medical conditions has been well known. Various devices have also been developed for application of laser energy to tissue inside of a patient.
In order to provide laser energy to tissue within a patient for such purposes as ablation of plaque from the walls of a blood vessel, a technique is required which can accurately apply the laser energy to the tissue. Various problems have been encountered in application of laser energy to tissues of a patient. For example, the laser passing through a glass window may cause the build up of burnt tissue or burnt blood cells at and around the point at which the laser exits the glass window. This black, carbonized material would in turn absorb the laser energy before it could strike the tissue and would at least partially block the laser energy from striking the tissues of the patient. This may damage the laser catheter device itself.
George S. Abela and Stephan E. Friedl, both among the inventors of the present application, obtained U.S. Pat. No. 5,061,265 on Oct. 29, 1991, entitled "LASER TREATMENT APPARATUS AND METHOD", hereby incorporated by reference. That patent discloses a dual hood arrangement whereby laser energy passes out through an inner hood having a window of transparent material and passes through an opening of an outer hood. By supplying pressurized flushing solution to within the outer hood, the flushing solution maintains the inner hood relatively clear of burned materials and flows out the same opening as the laser energy.
Among other prior patents, U.S. Pat. Nos. 4,860,743, issued Aug. 29, 1989 to George S. Abela and 5,041,109, issued Aug. 20, 1991 to George S. Abela, both disclose various laser catheters for treatment of cardiac conditions. Those patents, both of which are hereby incorporated by reference, disclose the use of electrode rings on the catheters for detection of conduction tissue. Such rings are also discussed in the Abela et al '265 patent mentioned above. The electrode rings allow one to locate tissue which is to be treated.
Although the above and various other designs of catheters have been quite useful, they have often been subject to one or more of several limitations or disadvantages. For example, positioning of the catheters within the patient has often been difficult and/or very time-consuming. The problem of positioning of the catheter for proper application of the laser energy is evident in treatment of arrhythmia conditions. Use of electrodes for mapping the conduction tissues of the heart has often been less efficient than desirable. The prior arrangements have often been less than satisfactory for AV (atrial-ventricular) nodal ablation. Generally, the fixed relationship between the laser beam and the electrodes has reduced flexibility in treating various conditions.
Among other problems with catheters in which flushing solution is used, body fluids may undesirably enter into the catheter through the port from which flushing solution is supplied during any halt in the supply of the flushing solution. That is, if one wishes to halt the supply of flushing solution temporarily, blood or other bodily fluids may enter into the port and the associated passage or channel used to supply the flushing solution.